在ExternalStorage中输出WritableWorkbook

Question

如何在ExternalStorage中输出WritableWorkbook，就像我创建Test.xls文件的情况一样：

String org = "test";

File file = null;
                File root = Environment.getExternalStorageDirectory();

                if (root.canWrite()) {

                    File dir = new File (root.getAbsolutePath() + "/Test");
                    dir.mkdirs();
                    file = new File(dir, "Test.xls");
                    FileOutputStream fos = null;

                    try {
                        fos = new FileOutputStream(file);
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    }
                    try {
                        fos.write(org.getBytes());

                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    try {
                        fos.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

这是我目前的WritableWorkbook代码：

@Override
    public void onClick(View arg0) {

        try {
            WritableWorkbook workbook = Workbook.createWorkbook(new File("output.xls"));
            WritableSheet sheet = workbook.createSheet("First Sheet", 0);

            Label label = new Label(0, 2, "A label record"); 
            sheet.addCell(label);

            workbook.write(); 
            workbook.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (RowsExceededException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (WriteException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }       
    }